The exemplary embodiments generally relate to computers and to communications and, more particularly, to admission requests and session control in computer networking.
Network admission control is important when delivering service applications to customers. Should a customer request Internet access, video-on-demand, video teleconferencing, IP telephony, interactive gaming, or many other service applications, the service provider must know that adequate bandwidth exists within the network infrastructure. When the customer pays for such service applications, the customer reasonably expects that the available network bandwidth will support such an application. For example, when a customer clicks a pay-per-view button and pays for a movie, that customer expects a “crystal clear” experience. If, however, network bandwidth is only marginally available and the quality of the experience is poor, the customer is understandably dissatisfied. Before a customer is offered a service application, the service provider should know whether that service application can be delivered and supported at a level of quality the customer expects.
Network admission control protocols help determine whether network infrastructure can support a service application. Network admission controls represent an interchange of information between the network elements that support these applications and the elements that initiate the applications. A customer can be offered multiple applications, such as multicast videos (that resemble broadcast TV), unicast video (that resemble pay-per-view services), games, and even voice services. What ever service the customer is offered, the network must be able to support the service. For the service application, there needs to be assurances that the long-lived session as a whole will have the results as necessary to normally operate. For example, in order to coordinate and make sure the next TV that gets turned on, or the next pay preview or the next phone call works, the signaling within the network must determine that the service can be supported. If the signaling determines that the service can be supported, the service is implemented. If, however, the signaling says “no”—the service cannot be supported—the customer's request is deferred. That is, the customer receives some kind of “busy” signal, pop-up message, or other indication that the customer's request will be queued and fulfilled as soon as bandwidth becomes available to support the quality needed for the requested application and/or service.
Network admission control protocols, then, help determine whether network infrastructure can support a service application. Problems with admission control are usually solved by protocols designed specifically for Quality of Service concerns. Admission control in IP networks usually utilizes RSVP protocols. RSVP protocols are typically used between computers and routers to reach reservations of capacity in IP packet networks. A Sessions Initiation Protocol (SIP) server launches an RSVP protocol, and the RSVP protocol creates the resources in the network or the resource reservation network. The problem, however, is that the RSVP linkage is a cumbersome mapping within the SIP server. Another problem is that the RSVP linkage is inefficient when trying to construct admission control across multiple services with different bandwidth requirements and with different service characteristics (such as in the case of unicast and multicast services). What is needed, then, is an admission control protocol that can successfully support multiple service applications, such as multicast service applications and unicast service applications.